1. Field of the Invention
The present invention relates to the manufacture of muffler devices for use in automotive exhaust systems.
2. Description of the Related Art
Mufflers are employed in automotive exhaust systems for reducing the sound from an automotive exhaust. Mufflers commonly include an inner space defined by a muffler shell body and muffler end caps. The inner space is divided into chambers by interior baffles that are generally oriented parallel with the muffler end caps. These mufflers also include inlet/outlet pipes joining the chambers and exhausting the gas.
The inlet/outlet pipes are inserted into apertures of the baffles. The inlet/outlet pipes and baffles are fixed together such that the inlet/outlet pipes run generally perpendicularly to the baffles. The baffles and inlet/outlet pipes are inserted into the muffler shell body such that the baffles are generally parallel to each other.
In practice, the muffler shell body is first formed and the muffler end caps are placed at each end of the muffler shell body. In accordance with common practice, the edge of each muffler end cap is folded over along the surface of the muffler shell body to form a mechanical lock joint so as to secure the end caps to the shell body and maintain the interior baffles in place. Each muffler end cap includes an aperture through which respective inlet/outlet pipes extend from the interior of the muffler. The attachment of the muffler end caps commonly employs a standard joint that is either a simple press cap joint or a flanged cap joint, both of which provide a lap seam joint. The standard joint widely in use is a flanged cap that is pressed into a muffler shell and welded on the lap joint all the way around the shell body. The issue commonly encountered with the use of such joints is the fit of the muffler end caps to the muffler shell body. Muffler shell bodies and muffler end caps tend to be inaccurate and these joints create larger than ideal gaps for the welding process. This can either cause failure of the joint, an increase in the weld cycle time, or added filler material being needed to seal the joint.